The Spanish theologian and polymath Miguel Serveto is burned alive in Calvins’s Geneva in October 1553. Because of his anti-Trinitarian theology, he is found guilty of blasphemy and questioning the divinity of Christ. Calvin attend the trial as star witness.
The execution moves the theologian Sebastian Castellio to advocate for religious tolerance in his book Concerning Heretics:
‘Men are puffed up with knowledge or with a false opinion of knowledge and look down upon others. Pride is followed by cruelty and persecution so that now scarcely anyone is able to endure another who differs at all from him. Although opinions are almost as numerous as men, nevertheless there is hardly any sect which does not condemn all others and desire to reign alone. Hence arise banishment, chains, imprisonments, stakes, and gallows.’
– Sebastian Castellio